Jacketed steam drier



June 21, 1955 P, E, oHLsQN ErAl. Re. 24,024

JACKETED STEAM DRIER Original Filed lay 16, 1951 2 SheetsP-Sheet 1 June2l, 1955 P, E, oHLsoN ErAL Re. 24,024

JACKETED STEAM DRIER original Filed may 16, 1951 2 sheets-sheet 2INVENTORS Pdzf] E.' Ofzsaz? Zawya/Hodge ATTORNEY United States PatentOiiice Re. 24,024 Reissued June 2l, 1955 24,024 JACKETED STEAM DRlERPaul E. Ohlson, Wilmington, and Edward A. Hodge, New

Castle, Del., assignors to The Pusey & Jones Corporation, Wilmington,Del., a corporation of Delaware Original No. 2,677,899, dated May 1l,1954, Serial No.

226,698, May 16, 1951. Application for reissue February 7, 1955, SerialNo. 486,746

l Claims. (Cl. 34-124) Matter enclosed in heavy brackets II] appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

The present invention relates to steam jacketed driers of the type usedin paper mills, food processing plants, industrial chemicalmanufacturing plants, and the like. Driers of the kind which areimproved by the present invention are to be distinguished from heavycast iron driers in which the entire interiors of the cylindrical drumsare filled with steam, since jacketed driers conventionally have theirinteriors open to the atmosphere and comprise a pair of concentric,steel cylinders, providing a closed space therebetween, into whichrelatively high pressure steam is delivered, and from which condensateis removed.

A primary object of the present invention is to provide means forincreasing the rate of heat transfer from the exterior surface of asteel jacketed drier to the material being dried.

To this end, au important object of the invention is to increase thevelocity of steam ow through the jacket space in the drier. Suchincreased velocity of steam ow exerts a scouringaction upon the innersurface of the outer cylinder and electively prevents the formation of afilm or layer of condensate on said surface, which, in conventionalpractice, acts as an insulating layer and reduces the rate of heattransfer from the steam to the cylinder. The scouring action, effectedby the improvements of the present invention, also effectively removesair and non-condensable gases from the jacket space, thereby furtherimproving the heat transfer rate.

it has been standard practice in the jacketed drier art to space theinner and outer cylinders substantially two inches apart, regardless ofthe diameter of the drier, which may vary from 36 inches to 144 inches.This relatively large jacket space results in numerous disadvantageswhich have not been appreciated or understood ln the prior art. Thevelocity of steam ow in the jacket ipace is insufcient to effect thedesired scouring action md the removal of condensate, air, andnon-condensable gases. Accordingly, at low speed, the condensate pudilesbadly near the bottom of the drier, thereby intert'ering with heattransfer and increasing the power reluired to rotate the drier. At highspeed, the condensate 'ims in a film around the entire inner surface ofthe outer :ylinder and interferes with heat transfer. Air and non-:ondensable gases remain in the jacket space because of nadequateventing and low rate of steam flow.

No attempt in the past has been made to control the [uality of the steamwithin the drier in such a manner as o effect maximum heat transfer. Nomeans have been irovided to effect even and uniform distribution ofsteam low over the entire inner surface of the drier.

The purpose of the present invention is to overcome ill of the foregoingdefects; to produce a sufficiently high 'elocity of steam tlow to scourair, water, and inconlensable gases; to effect even and uniformdistribution f steam tiow within the jacket space; and to control theluality of the steam within the jacket to etect maximum teat transfer.

As a result of shop experimentation and theoretical calculations, it hasbeen determined that a steam flow velocity, upon the introduction of thesteam into the jacket space, of feet per minute and a discharge velocityof low quality steam and condensate of 7 feet per minute or more isnecessary to produce the desired scouring action and to effect properremoval of condensate, air, and non-condensable gases.

The objects of the present invention are accomplished, as explained inconnection with the illustrative embodiments described below, bydecreasing the radial dimension of the steam space between the outer andinner cylinders to substantially 3A, of an inch, more or less, dependingupon the diameter of the drier; by dividing the jacket space into aplurality of longitudinally extending com partments; by delivering thesteam at high velocity to the leading ends of the compartment at aplurality of points through openings of accurately determined areas; andby providing means for removing low quality steam and condensateadjacent the trailing ends of the compartments through a plurality ofapertures of accurately determined size, to control the quality of thesteam and the velocity of discharge of steam and condensate. Improvedmeans for effecting these several results are shown in the illustrativeembodiment in the accompanying draw ings, in which:

Figure l is a vertical longitudinal section of a drier;

Figure 2 is a section taken on line 2--2 of Figure l, on a somewhatlarger scale;

Figure 3 is a section and end elevation taken on line 3 3 of Figure l;

Figure 4 is an enlarged fragmentary section through the inner and outercylinders and the steam delivery and condensate removalinstrumentalities; and

Figure 5 is a fragmentary axial section on an enlarged scale withcertain parts broken away.

A pair of hollow journals 10 and 11, interconnected by a central shaft12 may be supported in conventional manner by suitable bearings,represented diagrammatically at 13 and 14. The journals carry end platesor heads 15 and 16, which may have openings 17 therein so that theinterior of the drier is open to atmosphere. Secured to the outermargins of the two heads are a pair of inner and outer steel cylinders18 and 19, disposed in closely spaced concentric relation and spacedapart by end rings 20 and 21, to which they are welded, to provide aclosed jacket space 22.

As indicated in Figure 5, the heads may be reinforced by radial webs 23,extending from the inner cylinder 18 to a supporting ring 24, secured tothe journal 11 in any appropriate manner, as by bolts 25 extendingthrough a flange 26 integral with or mounted upon the journal.

The space 22 between the inner and outer cylinders is divided into aplurality of longitudinally extending compartments, by a plurality ofstainless, spring steel vanes 30, having their inner portions 31 weldedto the outer surface of the inner cylinder 18 and their outer edgeportions 32 bearing against the inner surface of the outer cylinder 19with spring pressure. As indicated by the arrows in Figures 2 and 4, thevanes are pitched forwardly and outwardly in the direction of rotation0l' the drier. Moreover, they extend longitudinally in angular relationto axial sections of the cylinder so that condensate engaged by theirleading faces tends to low, under the influence of inertia, gravity, andcentrifugal force, toward their trailing ends.

The inner cylinder 18 is provided with a plurality of rows of apertures33, one row being disposed adjacent the leading faces of each of thevanes 30, at the trailing end of each compartment in the space 22. Theseaper tures provide means for the discharge of condensate, lowqualitysteam, air, and non-condensable gases from the several compartments; andsuch tlow is facilitated by the scooping action of the vanes.

The inner cylinder 18 is also provided with a plurality of rows ofopenings 35, disposed in parallel relation to the apertures 33 with onerow positioned behind each vane and near the leading end of eachcompartment in the space 22. As hereinafter explained, steam flowsthrough these openings into the several compartments. ln order toprevent the direct impingement of the steam upon the inner surface ofthe outer cylinder, at points in alignment with the openings, and toeffect a uniform dispersal of the steam, the openings 35 are fitted withnipples 36, having closed, circular outer ends, constituting batlles 37and laterally directed, slotted openings 38 and 39, so that the steam isdirected laterally. as distinguished from radially, into the jacketspace 22.

Upon the inner surface of the inner cylinder, in alignment with each rowof apertures 33, there is an outwardly facing trough 40, consisting of aU-shaped sheet metal strip welded to the cylinder 18 and disposedlongitudinally in angular relation to axial sections of the drier, inthe same manner as the vanes and the rows of apertures. Accordingly,condensate flowing inwardly through the apertures 33 into the troughstends to flow longitudinally toward the trailing ends of the troughs or,in other words,

toward the left in Figure l.

At the latter end, each trough is connected to a radial pipe 4l havingits inner end connected to an axial pipe 42, extending through thejournal ll and bearing 14, to a suitable condensate collecting trap andreturn steam line, not shown.

Adjacent each trough 40 is a second trough 45, which may consist of anL-section sheet metal strip, welded to the Usection strip 40 and to theinner surface of the inner drum 18, as illustrated in Figure 4. Eachtrough encloses the associated row of openings 35 and nipples 36. At theright hand or leading end, each trough 45 is in communication with aradial steam delivery pipe 46, extending into the interior 47 of theright hand journal l0, to which is connected a steam supply pipe 48.

In many cases, particularly where the length of the drier exceeds thecircumferential dimension, it has been found highly advantageous todivide the space 22 into a plurality of separate compartments, bypositioning circumferential range 50 in the jacket space. the entirespace may be divided into four compartments or chambers, longitudinallyof the drum and each of these compartments again divided by the fins orvanes 30. One circumferentially extending ring 50 may be positionedmidway between the end rings 20 and 2l, and two other circumferentialrings 50 midway between the first mentioned one and the end rings. Suchan arrangement prevents a direct longitudinal ow from the steam inletsto the outlets; results in a more uniform, circumferential flow of steamin the several compartments, and provides an improved and more thoroughscouring action for the removal of air and non-condensable gases. Thisarrangement has been found to be of importance and to produce highlyadvantageous results in elongated driers, such as those having a inchdiameter and a 23S-inch length.

In the operation of the apparatus of the present invention, high qualitysteamat relatively high pressure, in the neighborhood of 125 pounds persquare inch is delivered through pipes 4B and 46 to the interior of thelongitudinally extending distributing troughs 45, from which it owsthrough the nipples 36 into the several compartments, into which thespace 22 is divided by the vanes 30. The high quality steam isdistributed uniformly and evenly throughout the compartments and givesup its latent heat to the outer cylinder 19, which results in areduction in the quality of the steam, considerable condensation on theinner surface of the outer drum, and a high velocity steam flow. The lowquality steam flows from the space 22, inwardly through apertures 33into the trough 40, with a relatively high velocity flow, which Forinstance, l

lll

lill

results in a scouring action within the space 22, tending to drivecondensate, air, and non-condensable gases toward the trailing end ofeach compartment. The vanes 30 exert a scooping action on the condensateand force it to ow through the apertures 33 into the trough 40.

Because of the angular disposition of the troughs 40, from end to end,the condensate, through the influence of centrifugal force, inertia, andgravity is caused to llow longitudinally in each trough toward thetrailing end thereof, where the condensate is received by `the radialpipes 46 for flow through the interior of the journal ll, and fordischarge through the pipe 42.

ln order that the quality of the steam may be reduced from substantiallywhen it is introduced, to substantially 10%, when it is dischargedthrough the apertures 33, to produce a high velocity ow and to give up amajor portion of its latent heat, it has been found that the totalcross-sectional area of the apertures 33 should equal approximately 10%of the total cross-sectional area of the steam space 22. Moreover, inorder that the velocity of the flow of steam in the space be high, theradial dimension thereof should be small.

Experiments and theoretical calculations have demonstrated that a drierin accordance with the present invention, using steam pressures ofbetween and l80 pounds per square inch results in an increase of heattransfer of between 22% and 29%, as compared with prior steam jacketeddriers, operating at similar pressure, but not provided with theimprovements of the present invention.

lt must be understood that the invention is not limited to the detailsof construction shown in the accompanying drawings and described above,as many modifications will occur to those skilled in the art from aconsideration of this disclosure. The invention includes allmodifications coming within the scope of the appended claims and theirequivalents.

We claim:

l. A drier comprising a pair of concentric, closely spaced, inner andouter cylinders mounted for rotation in a predetermined direction andhaving the interior of the inner cylinder open to the atmosphere,gas-tight sealing means closing the ends of the space between thecylinders, r1 plurality of vanes extending longitudinally from end toend of the cylinders and dividing the space therebetween into aplurality of longitudinal compartments, the inner cylinder having a rowof openings behind each of said vanes and a row of apertures ahead ofeach vane, means for delivering steam through each row of openings tosaid compartments adjacent the leading ends thereof and trough meanscarried by the inner surface of the inner cylinder registering with therows of apertures for collecting condensate and low quality steamflowing through the apertures in the inner cylinder.

2. A dried comprising a pair of concentric, closely spaced inner andouter steel cylinders of substantially equal wall thickness mounted forrotation about their common axis in a predetermined direction, gas-tightsealing means closing the ends of the space between the cylinders, aplurality of vanes extending longitudinally from end to end of thecylinders, dividing the space therebetween into a plurality oflongitudinally extending oompartments, said vanes being forwardly andoutwardly pitched from the inner to the outer cylinder, the innercylinder having a row of openings behind each of said vanes and a row ofapertures ahead of each vane, means for delivering high quality, highpressure steam, through each row of openings to the said space andtrough means carried by the inner surface of the inner cylinderregistering with the rows of apertures for collecting condensate and lowquality steam flowing from said space through said apertures.

3. A drier comprising a pair of concentric, closely spaced inner andouter steel cylinders of substantially equal wall thickness mounted forrotation about their common axis in a predetermined direction, gas-tightscaling means closing the ends of the space between the cylinders, aplurality of vanes extending longitudinally from cnd to end of thecylinders, dividing the space therebetween into a plurality oflongitudinally extending compartments, said vanes being secured to theouter surface of the inner cylinder and projecting outwardly inforwardly pitched relation into contact with the inner sur face of theouter cylinder, means for delivering steam to said compartments behindeach of said vanes, said inner :ylinder having a row of aperturesadjacent the leading face of each vane for the inward tlow of lowquality steam and condensate, and a plurality of troughs on the innersurface of the inner cylinder registering with said rows of aperturesfor collecting the inwardly flowing condensate and low quality steam.

4. A drier comprising a pair of concentric, closely spaced inner andouter steel cylinders of substantially equal wall thickness mounted forrotation about their common axis in a predetermined direction, gas-tightsealing means closing the ends of the space between the cylinders, aplurality of vanes extending longitudinally from rnd to end of thecylinders dividing the space therebetween into a plurality oflongitudinally extending compartments, said vanes being secured to theouter surface of the inner cylinder and projecting outwardly inforwardly pitched relation into contact with the inner sur- Face of theouter cylinder and disposed longitudinally in angular relation to axialsections of the cylinders, whereby longitudinal ow is imparted tocondensate engaging the vanes, means for delivering steam to thecompartments `adjacent the leading ends thereof, the inner cylinderhaving a row of apertures adjacent the trailing end of each compartmentopposite the leading face of the associated vane for the inward flow ofcondensate, and an outwardly lacing trough secured to the inner surfaceof the inner .-ylindet', enclosing each row of apertures to receive saidsondensate.

5. A drier comprising a pair of concentric, closely spaced inner andouter steel cylinders of substantially :qual wall thickness mounted forrotation about their :ommon axis in a predetermined direction, gas-tightseallng means closing the ends of the space between the cylinlcrs, aplurality of vanes extending longitudinally from :nd to end of thecylinders dividing the space there- `setti/een into a plurality oflongitudinally extending oompartments, said vanes being secured to theouter surface sf the` inner cylinder and projecting outwardly inforwardly pitched relation into contact with the inner surface of theouter cylinder and disposed longitudinally in angular relation to axialsections of the cylinders, whereby longitudinal flow is imparted tocondensate engaging the vanes, means for delivering steam to thecompartments adjacent the leading ends thereof, the inner cylinderhaving a row of apertures adjacent the trailing end of each :ompartmcntopposite the leading face of the associated vane for the inward flow ofcondensate and an outwardly facing trough secured to the inner surfaceof the inner :ylinder, enclosing each row of apertures to receive said:ondensate, each of said troughs being disposed in similar angularrelation to an axial section of the cylinders, whereby longitudinal tlowis imparted to the condensate received therein, and means connected tothe trailing end of each trough for removing condensate therefrom.

6. A jacketed steam drier comprising a pair of concentric, closelyspaced inner and outer cylinders, means closing the ends of the spacetherebetween, means extending longitudinally from end to end of thecylinder for dividing said space into a plurality of longitudinalcompartments, a row of openings in the inner cylinder adjacent theleading end of each compartment, a row of apertures of reduced totalcross-sectional area as cornpared to said openings extending through theinner cylinder adjacent the trailing end of each compartment, apluralitv nf pairs of adjacent troughs extending longitudinally alongthe inner surface of the inner cylinder with one trough of each pairembracing the openings of one compartment and the adjacent trough ofeach pair embracing the apertures of the compartment ahead thereof inthe direction of rotation of the drier, means for delivering steam tothe first trough and means for removing condensate from the secondtrough.

7. A drier in accordance with claim 6 in which the means for dividingthe space between the cylinders into said compartments comprises aplurality of longitudinally extending vanes secured to the outer surfaceof the inner cylinder, projecting outwardly in forwardly pitchedrelation and contacting the inner surface of the outer cylinder.

8. A drier in accordance with claim 7 characterized in that the vanesand the troughs are disposed in angular relation to axial sections ofthe cylinder, whereby longitudinal flow is imparted to condensateengaging the vanes and to condensate received in the second trough, saiddrier being further characterized by the inclusion of means for removingcondensate from the trailing end of the second trough of each pair.

9. In a jacketed drier of the type having an open interior andconcentric inner and outer cylinders defining a closed annular steamspace therebetween, a central shaft, journal means therefor, means fordelivering steam to said space through one journal and means forremoving condensate through the other journal, the improvement in thesteam delivery and condensate removal means which comprises a pluralityof forwardly and outwardly pitched vanes, secured to the outer surfaceof the inner cylinder making contact with the outer cylinder anddividing said space into a plurality of longitudinal compartments, a rowof openings extending through the inner cylinder behind each vane, a rowof apertures extending through the inner cylinder adjacent the leadingface of each vane, means for delivering steam to all of the openings, atrough on the inner surface of the inner cylinder enclosing each row ofapertures, and means connecting each trough to the condensate removalmeans extending through said other journal.

10. In a jacketed drier of the type having an open interior andconcentric inner and outer cylinders defining a closed annular steamspace therebetween, a central shaft, journal means therefor, means fordelivering steam to said space through one journal and me s for removingcondensate through the other journal, vt e improvement in the steamdelivery and condensate removal means which comprises a plurality offorwardly and outwardly pitched vanes, secured to the outer surface ofthe inner cylinder making contact with the outer cylinder and dividingsaid space into a plurality of longitudinal compartments, a row ofopenings extending through the inner cylinder behind each vane, a row ofapertures extending through the inner cylinder adjacent the leading faceof each vane, a trough on the inner surface of the inner cylinderenclosing each row of openings, and means connecting each trough to themeans for delivering steam through the first mentioned journal.

l1. In a jacketed drier of the type having an open interior andconcentric inner and outer cylinders defining a closed annular steamspace therebetween, a central shaft, journal means therefor, means fordelivering steam to said space through one journal and means forremoving condensate through the other journal, the improvement in thesteam delivery and condensate removal means which comprises a pluralityof forwardly and outwardly pitched vanes, secured to the outer surfaceof the inner cylinder making contact with the outer cylinder anddividing said space into a plurality of longitudinal compartments, a rowof openings extending through the inner cylinder behind each vane, a rowof apertures extending through the inner cylinder adjacent the leadingface of each vane, a trough on the inner surface of the inner cylinderenclosing each row of openings, means connecting each trough to themeans for delivering steam through the tirst mentioned journal, a secondtrough positioned adjacent each of the first mentioned troughs on theinner surface of the cylinder enclosing each row of apertures and meansconnecting each of the second mentioned troughs to the condensateremoval means extending through the second journal.

I2. A drier comprising a pair of concentric, closely spaced, inner andouter cylinders mounted for rotation in a predetermined direction andhaving the interior of the inner cylinder open to the atmosphere,gas-tight .mealing means closing the ends of the space between thecylinders, at least one flow resistance ring extending circumferentiallyof the cylinders intermediate said sealing means, a plurality of vanesextending longitudinally of the cylinders, said rings and said vanesdividing the flow space between the cylinders into a plurality ofsegmentalannular compartments, the inner cylinder having a row ofopenings behind each of said vanes and a row ol apertures ahead of eachvane, means for delivering steam through each row of openings to saidcompartments adjacent the leading ends thereof and trough means carriedby the inner surface of the inner cylinder registering with the rows ofapertures for collecting condensate and low quality steam flowingthrough the apertures in the inner cylinder.

I3. A drier comprising a pair of concentric, closely spaced inner andouter steel cylinders of substantially equal wall thickness mounted forrotation about their common axis in a predetermined direction, gas-tightsealing means closing the ends of the space between the cylinders, atleast one flow resistance ring extending circumferentially of thecylinders intermediate said sealing means, a plurality of vanesextending longitudinally of the cylinders, said rings and said vanesdividing the space between the cylinders into a plurality ofsegmental-annular flow compartments, said vanes being forwardly andoutwardly pitched from the inner to the outer cylinder, the innercylinder having a row of openings behind each of said vanes and a row ofapertures ahead of each vane, means for delivering high quality, highpressure steam, through each row of openings to the said space andtrough means carried by the inner surface of the inner cylinderregistering with the rows of apertures for collecting condensate and lowquality steam flowing from said space through said apertures.

14. A jacketed steam drier comprising a pair of concentric, closelyspaced inner and outer cylinders, means closing the ends of the spacetherebetween, at least one resistance ring extending circumferentiallyof the cylinders intermediate said closing means, a plurality of vanesextending longitudinally of the cylinders, said rings and said vanesdividing the space between the cylinders into a plurality ofsegmental-annular ow compartments, a row of openings in the innercylinder adjacent the leading end of each compartment, a row ofapertures of reduced total cross-.sectional area as compared to saidopenings extending through the inner cylinder adjacent the trailing endof each compartment, a plurality of pairs of adjacent troughs extendinglongitudinally along the inner surface of the inner cylinder with onetrough of each pair embracing the openings of one compartment and theadjacent trough of each pair embracing the apertures of the compartmentahead thereof in the direction of rotation of the drier, means fordelivering steam to the first trough and means for removing condensatefrom the second trough.

l5. In a jacketed drier of the type having an open nterior andconcentric inner and outer cylinders defining a closed annular steamspace therebetween. u central shaft. journal means therefor, means fordelivering steam to said space through one journal and means forremoving condensate through the other journal, the improvement in thesteam delivery and condensate removal means which comprises a pluralityof forwardly and outwardly pitched vanes, secured to the outer surfaceof the inner cylinder making contact with the outer cylinder, at leastone ring extending circumferentially of the cylinders, said vanes andsaid resistance ring dividing the flow space between the cylinders intoa plurality of segmentalannular compartments, a row of openingsextending through the inner cylinder behind each vane, a row ofapertures extending through the inner cylinder adjacent the leading faceof each vane, a trough on the inner surface of the inner cylinderenclosing each row of openings, means connecting each trough to themeans for delivering steam through the first mentioned journal, a secondtrough positioned adjacent each of the first mentioned troughs on theinner surface of the cylinder enclosing each row of apertures and meansconnecting each of the second mentioned troughs to the condensateremoval means extending through the second journal.

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